The Unit of Weight Called the Grain

A Weight Specified Down to the Fraction

In seventeen hundred and ninety-two, the United States of America established its currency as the dollar. The weight of a one-dollar silver coin was three hundred seventy-one and one-quarter grains of pure silver. This was a specification written into the articles of law, down to the fraction.

Why such a precise number? It was a manifestation of the will to base value not on a promise, but on the silver on the scale. This weight was determined by actually measuring the Spanish eight-real silver coins that circulated the world. The newly independent nation aligned its currency with a piece that the world already trusted. While the system of calculation was new—the decimal system—its weight was tied to long-standing trust.

Currency Derived from a Bean

In distant India, too, the history of currency begins with weight. The ancient silver coin called the Karshapana was named after the Sanskrit unit of weight, the Karsha. Its standard was the weight of a certain type of bean called the ratti. The seed of a plant was the origin of coinage weight.

Surviving examples generally fall within the range of fifty to fifty-two grains. Regardless of country, era, or workshop, this weight alone does not change. That they be the same when placed on a scale—that was the only promise given to these pieces of silver. Not what was depicted, but how much it weighed. This is where currency began. In a book called the *Arthashastra*, the term *rupyarupa* is recorded as a name for a silver coin.

Five Grains in Six Hundred Years

The Indian silver coin bearing the name rupee did not change its weight for a long time. The silver tanka of Iltutmish in the thirteenth century was one hundred seventy-five grains. The rupee of Sher Shah Suri was one hundred seventy-eight grains. And the uniform coinage of eighteen hundred and thirty-five was one hundred eighty grains.

In six hundred years, it had shifted by only five grains. No one wanted to change this weight because the people who received it were accustomed to it.

The Dollar, Redefined in Gold

The American dollar began its journey with the weight of silver. It was the start of a bimetallic standard, anchored to two metals: gold and silver. However, this definition was later rewritten. The Gold Standard Act of nineteen hundred defined one dollar as twenty-five and eight-tenths grains of gold of nine-tenths fineness.